Controller for electrically-operated skip hoists



July 22', 1930.

P. B. HARWOOD CONTROLLER FOR ELECTRICALLY OPERATED SKIP HOISTS 2 Sheet s-Sheet 1' Filed Oct. 4, 1926 U DUDDD i: m E i 00 00 O0 5 a s a 3 s m m a 1 o: az Q ooo 000 00 0% @W v D 0 H U m D D n Q m N W" R I IINVENTOR. .V BJlaMuoML BY uuuuuuuuuuuuuuuuuul l ATTORNEY Julv 22, 1930.

CONTROLLER ile ct- 1926 2 Sheets-Sheet 2 INVENTOR. 2mm 3mm M A TTQRNEY Patented July 22, 1930 raisin?" 3. mirtwoon'pr MILWAUKEE,lwrscoizsm, .assienon, BY MESNE ASSIGIL:

.' 'ro cu'rnmnammn, 1101? nnLAwenE me, or MILWAUKEE, WISCONSIN, A CORPORATION.

-oon'rRoLLER r012 ELEcrRIcALLY-orEn-Aimn "sK'Ir HoIsrs Application filed October 4, 1926. Serial No. 139,425.

invention relates to controllers for electrically goperated skip -hoists.- ,llie inyention relates-more particularly to controllers forvdouble bucket skip hoists althongh eertain tfeatures thereof may be advantageously employed in cont-rollers for skip hoists of the single bucket type.

- .The invention hasamong its objects to provide an improved controller for double bucket skip hoists wherein provision is made for insurin raising of the loaded bucket and lowering the empty bucket upon successive operationsof a single starting switch.

Another object is to provide a controller of the aforesaid characten including control means for stopping the skip hoist at any pomt and for insuring restarting thereof in the proper di 'ection to raise the loaded bucket nponoperation'of the aforementioned start- 90 ing;switch. Another object is to provide a controller of the aforesaid character wherein provision is made for lowering a loaded bucket from any point at a reduced rate of speed by operationof a down push button. Another object is to provide a controller of the aforesaid character having emergency control means associated therewith which provides for operation of the skip hoist in either direction at either a low or a high speed. Various other objects and advantages of the invention will hereinafter appear.

The'acc ompanying drawings illustrate an embodiment of the invention which will now be described, it being understood that the embodiment illustrated may be modified in certain respects without departing from the spirit and scope of the appended claims.

In the drawing,

Figure l is a schematic and diagrammatic view of a controller embodying the invention, the circuit connections being omitted.

Fig. 2 is an across-the-line diagram of the motor connections together with the control 13 circuit for a brake associated with the motor,

and

Fig. 3 is an across-the-line diagram of the control circuits for the several control elements illustrated in Fig. 1.

so Referring to Fig. l the same illustrates a motor-M for driving a drum D ofa'skip hoist. The operating cable or cables extend in the usual manner around dru'm D and are connected to the skip buckets so thatduring operation of the motor in one direction-oneof the ski buckets is-raised and the otheris lowere while reversal of the motor reverses. the direction of operation of the skip buckets. The motor M may be of any desired type'gbuta in the embodimentillustrated the same is shown as of the compound type. Als0,;in the embodiment illustrated the motor M is providedwith an electromagnetically operated:- brakeB. 7'5

As shown in Figs. 1 and 2 the armature circuitjfor motor M is controlled by a knife switch -1, an electromaguetica-lly. operated main switchf2, and two sets of electromag netically operated reversing switches 34 and 5 6 and the current in said-gcircuit is controlled byinea'ns of series resistances R. to R inclusive, and shunt resistances R to R, inclusive. Resistances-R to R: inclu-- sive, have electromagnetically operated control switches 7 to 11 associated therewith, the switches 7 to 10 being arranged to connect resistances R to R? respectively in shunt with the resistance R and the switch 11' being arranged to shunt resistances R to R inclusive. Resistances .R to R", inclusive, are controlled by electromagnetically operated switches 12 to 16, respectively, the switches 12 to 15. being normally closed and the switch 16 being normally open. The shunt field F of the motor is controlled by a double pole double throw knife switch 17, said knife switch being adapted in one position to connect said field to lines L to L and being adapted in its other position to connect a discharge resistance across the terminals of said field. The brake B associated with the motor is controlled by a normally open electromagnetic switch 18. Y

The control means for the set of reversing switches 3- includes a normally open doubie pole electromagnetically operated relay 20 While the control means for the other set of reversing switches 56 includes a normally open double pole electromagnetically operated relay 21. Each of the relays 20 and 100 hit.

energized to'move the selector relay through the medium of safety switches in cluding an overspeed governor switch 25,

overload switches 26 and-27 andra pair' of slack cable switches 28 and 29, all of said switcheslbeing arranged in series in the ener-' gizing-hircuits ofthe aforementioned relays. In addition to the aforementioned switches relays 201-to'23, inclusive; 1 are a controlled through the medium of a-Stop snap switch 30, and a normally open Hoist pusnbutton switch-31;,- said switches being adapted as hereinafter set forth tocontrol the afore' mentioned relays through the medium of the aforedescribed safety devices and a selector relay35.

Relay 35 is of the double pole double throw type, the same beingl-provided with an operating winding 35 and a latching coil35". Thearrangeinent is such that upon energizati'onzbf theioperatingwinding 35* the selector-switch ismoved to one extreme position: and -is.held therein by a latching mechanism andmpon deenerg'lzation of winding 35f and energization of-"coil '35 the latching 'inechanism isreleasedto permit the selector switch-to return tonormal position. 'As hereinafter-set forth the operating winding 35 of .theaselector switch'35 is controlled through the medium of a limit switch 36 while the trip coil 35" is controlled through the medium of a limit switch 37. The arrangement is such that when one of the buckets of the skip hoist is brought into one extreme position the operating winding 35 is 35 into its latched in position while when said bucket is moved into its opposite extreme position the trip coil 35 is energized to permit the selector rclay 35 to return to normal position.

"'As hereinafter set forth the selectonrelay 35 selects the direction of operation of the motor so that upon. successive operations of the Hoist push button 31 raising of the loaded 4 skip bucket is always insured. The limit switches 36 and 37 also serve as hereinafter set forth to insure interruption of the energizing circuits of relays 20 to 23, for stopping of the motor when the skip buckets are moved ,into their limits.

' Accelerating switches 7 to 11, inclusive, are controlled through the medium of an electromagnetically operated timing device 40 and relays 41 to 45, inclusive, having operating windings arranged in series with re- R to R respectively. Relays 41 c1. site, are each adapted under given more... in the notor circuit to establish energizing circuits for accelerating switches T'to 11 respcctitely wh le the timing device 40 is adapted to establishenergizing circuits for. said. accelerating switches independently of said relays if the latter do not close within.

sistances a given interval. Tiiniing 'devicd'lo i a well li'i'iown type, thesamejbmgf' ovided \Villil series of contact fingersw nch "are adapted to close successively;;against the action of a dash potupon energization of an operating winding 4.0%,

The control means for slow down switches 12, Band 14: includes limit switches to 55, inclusive. :Ls hereinafter set? forth limit' switches 50,51v and 52 arc'adapted 'toi'bli'o perated in the order named prior "to 'lim'it' switch 37-during movement of the slap hoist into one of its limits, while limit switches-53, 54: and are adapted tobekoperated in-' the order named prior to limitswit'ch 36 during movement of t i sliip hoi'st into an oppositelimit.

ling brake B controlled by relays 20 and 21,- and as hereinafter set-forth s'aidswitch is also controlled by a relay arranged 'infseries in the armatu re circuit ofthe: motor.

Vitii the control means above described, depression of the hoist push button 31 causes the motor to be brought up to speedeiito matically to operate theskip hoist iii'a dire'o-E tion te raise the loaded bucket, and"whei'i the skip hoist moves into either'of its limits the same is automatically stopped. Furthermore as hereinafter s'et'forth the skip 'hoist can be stopped at any intermediate point by opening the restarted by the push button 31 in a direction to raise the loaded bucket. x

In some instances it is desirable to provide means whereby the operator can lower a As before stated the switch 18 for controlstop switch 30 and can then be 1 5 loaded bucket and for this purpose relays 60 no and 61 are provided which effect substantialiy the same control. as relays 20 and 21 respectively. Relays G0 and-G1 are both controlled hy electro-rcsponsive relays 62 and 63 which also control the accelerating switch 16. Relays (32 and 63 are controlled by'a lowering push button 64 through the medium of certain of the contacts of the selector switch 35 and said lowering push button also acts through the medium of said selector switch 1% to control relays 65 and 66 which are adapted as hereinafter set forth to control the slow down switches 12, 13 and 14. I i

t is desirable to provide in addition to the operators control means an emergency con- 13:.

master drum 70 by means of a 12 pole double 1;:

throw knife switch 71. For control of the skip hoistjfrom the .push button station the transfer switch-71 is maintained in its lower position as shown in Fig. 1, and when it is desired to control from the emergency drum the same is moved into its upper position. The master ,drum includes stationary contacts 72 toi8 1',- inclusive, movable contact 72 and-731m coo crate with contact 72 and 73 and two sets'o movable contacts arranged on opposite side1of:,said stationary contacts. One of said sets of movable contacts includes contacts=74 to 79, while the other set of movable contacts includes contacts 74:", 75 76", 7 9 80 and 81". One of the poles of the k'nifegswitch 71 serves to establish an energizing'circuit for a no voltage relay 90, and said relayserves as hereinafter set forth to necessitate return-of the master drum 70 to ofi'pqsition; as a prerequisite to starting of the-motor. t I 7' ,Inaddition; to the aforedescribed control meansm knifej'swi-tch'91 isprovided for controlling the line.=,connections of all of the aforedescribed relays and such line connections are further controlled by a normally open relay 92 having its operating winding permanently connected in series with the shunt F1- J; .i Y I The' operation of the aforedescribed controller together with the circuit connections therefor,- -.willnow be more, fully described in connection ;w ith ,Figs. 2 and 3. Assumingthat'all ofthe control elements are in the position shownin Fig. l and upon closure of the stop snap switch 30 and depression of the hoist puslrbutton 31, relays and 22 are energized by a circuit extending from line L through the over speed governor 25 and overload devices 26 and 27 through one pole of thefiransfer switch 71, through the stop button 30;and another pole of the transfer switch 71, through normally closed auxiliary contacts ll -associated with accelerating switch 11 through the hoist push button 31, through the upper left hand pole of the selector relay and through the operating windings of the relays 20 and 22 in parallel, through down contacts of relays 23 and 65 through the lower pole of the limit switch 37 and thence through the normally closed auxiliary contacts 7" of accelerating switch 7 and the slack cable switches 28 and 29 to line L it being as sumed that the relay 92 is closed due to current in the shunt field circuit. Upon closure of relay 22 the left hand pole thereof shunts hoist switch 31 to establish a maintaining circuit for said relay 22 and also relay 20. Also upon closure of relay 22 the right hand pole thereof energizes slow down switches 12, 13 and 14 through the medium of limit switches 50, 51 and 52 and the auxiliary contacts associated with reversing switch 3 while the lower pole of said relay prevents energization of relays 21 and 23. Upon closure of relay 2( the set of reversing switches 3-4 is energized bya circuitex'tending from line L through the lower pole of limit switch .37,

through one pole of the} transfer switch 71 through the left hand pole of relay 20 and another pole of the transfer switch'71 to and through the operating windings of reversing switches 3 and 4 in parallel and through the lower pole of limit switch37, contacts 7 b and slack cable switches 28 and29 to'line L Also, immediately upon response ot reversing switch 4 the main switch 2and acceleratingswitch 15 are energized: by a circuit extending from line L to the relay 20 as already. traced, through the right hand pole of said relay, through one pole of the transfer switch 70 to and through the operating-windings of main switch 2 and accelerating switch 15 in parallel, through auxiliary contacts l: associated with reversing switch 4 and'thence through the lower pole of limit switch-37 to lineL. as'already traced. Switch 4 in respending also by-passes contacts 7" by means of its auxiliary contacts 4. Upon closure of main switch 2 and reversing switches3+4 the motor starts to operate at aueducedrspeed with the series resistances R to R in'circuit therewith and the shunt resistances R to :R excluded from circuit. Immediately-upon starting of the motor, the series brake-(relay 56 closes andthe operating windingxof the brake switch 18-is then connected in parallel with the operating: windings of inain switch 2 and accelerating switch .15. ':Brake' switch 18 in responding-.maintains itself-through the medium of auxiliary contacts 18 and conmeets the brake operating "winding between lines LL through the-main switch-2.

. Upon the closure of accelerating switch 12 the timing device is energized by a circuit extending from line L through the normally closed down contacts of relays 62 and 63 through one pole of thetransfer switch 71, through auxiliary contacts 11 of accelerating switch 11 through auxiliary contacts 18 associated with the brake switch 18 to and through the operating winding 40 of said timing device through auxiliary contacts 12 of accelerating switch 12 through the lower pole of the limit switch and thence through the auxiliary contacts of reversing switch 3 to line L Immediately upon establishment of the motor circuit the relay 41 is energized and when the current in the motor circuit drops to a given value said relay closes to establish an energizing circuit for the accelerating switch 7 extending from line L through the normally closed contacts of relays 63 and 62 through one pole of the transfer switch 71 through said series relay and the operating winding of the accelerating switch 7 and thence through the auxiliary contacts 2 associated with main switch 2 to line L. If the series relay 41 does not return to normal position prior to movement of the first contact finger of the timing device-40 into closed position'the operating winding of switch 7 will be connected directly to line L by said contact finger. Upon closure of accelerat ing switch 7 resistance R is connected in parallel with resistance It and relay 42 responds. Under given current conditions in the motor circuit relay 42 returns to normal position-to energize the operating winding of accelerating switch 8, such energizing circuit'extending-from line L through the normally closed contacts of relays 62 and 63 through one pole of the transfer switch 71, through-the auxiliary contacts 11 of accelerating switch 11, through series relay 42 and the operating winding of accelerating switch 8, through the auxiliary contacts 7 of accel crating switch 7 and thence through the auxiliary contacts 12-of accelerating switch 12, throughithe lower pole of limit switch and the auxiliary contacts associated with the reversing switch 3 to-line L. If the series relay 42-does not return to normal position prior tormovement of the second contact finger'of the timing device into closed position accelerating-switch 8 is energized independently of said relay by connection thereof directlyito line L. Accelerating switch-8 in responding connects resistance R in parallel with resistances R and R and series-relay 43-then responds. Under given current conditions in the motor circuit relay 43 returns toinori'nal position to establish an energizingcircuit for the accelerating switch 9 extending from line L through the series relay 43, the auxiliary contacts 8 associated with accelerating switch 8 and through the operating 3 winding of said accelerating switch to line' L If the relay 43 does not return to normal position within a given interval the third contact of timing device 40 closes to connect-the operating winding of accelerating switch 9 to line L independently of the series relay 43. Accelerating switch 9 in closing connects resistance Rt in shunt with resistances R, R and R and the series relay 44 responds. Under given current conditions in the motor circuit relay 44 returns to normal position'to connect the operating winding of accelerating switch 10 across lines L. f through the medium of the auxiliary contacts 9 associated with accelerating switch 9. If relay 44 does not return to normal position within a given interval the fourth contact finger of the timing device 40 closes to connectthe operating winding of accelerating switch lO-to line L. Accelerating switch 10 in closing connects'resistance R in shunt with resistances R, R R and R for further acceleration of the motor. Series relay 45 then responds to current in the motor circuit and under given current conditions the same returns to normal position to energize accelerating switch accelerating switch 11 fthe same interrupts the aforedescribed energizing circuit for timing device 40 by opening of the auxiliary contacts 11 and 'said accelerating switch maintains itself in closed position by a circuit extending from line-L through the'normally closed contacts of relays 63 and-"62 through a pole'of the transfer switch 71 through auxiliary contacts ll associated with said accelerating switch through the operating winding of said accelerating switch through auxiliary contacts 12 of accelerating switch 12 through-the lower pole of limit switch 50 and thence through the auxiliary contacts associated with reversing switch 3 to line L. The skip hoist will now operate'to bring the loadcdbu'cket into its upper position and during movement of the bucket into such position l1IDlt 'SW1t ChES 5O, 51, '52 and 37 are operated in the order namecL- Upon opening of limit switch 50 the upper pole thereof interrupts the aforedescribed energizing circuit for accelerating switch 12 and switch'12 in closing includes resistance R in the motor circuit to reduce the motor speed. Also upon opening of-limibswitch'50 the lower pole thereof interrupts the afore'described' energizingcircuit for accelerating switches 8 and 11 and switch 8' in opening causes accelerating switches 9 and 10 to open. Resistances Fi R and R are thus excluded from the motor circuit while accelerating switch 7 is maintained in closed position by the auxiliary contacts of main switch 2 to connect resistance R in shunt with R. Opening of limit switches 51 and 52 effects deenergization of accelerating switches 13 and 14 in the order named to include resistances R and R in the motor circuit. The skip hoist then opens the final limit switch 37 which interrupts the aforedescribed energizing circuits for main switch 2, reversing switches 3-4, accelerating switch 15, brake switch 18and the relays 20 and 22. Main switch 2 in openin deenergizes accelerating switch 7 for exc usion of resistance R and the motor is then brought to rest under the action of its brake B.

he controller is now set so that if the hoist button 31 is again operated the motor will be reversed to elevate the bucket which was formerly. empty but which, it is assumed, is now loaded. Such setting of the controller is obtained by means of the selector relay 35. Upon the aforedescribed movement of the skip hoist into its limit. the. upper pole of the limit switch 37 establishes an energiz ing circuit for the trip 001135 of the selector relay 35, suchenergizing-circuit extejiding'from 'line' L through the aforementioned pole of limit switch 37 through saidtrip coil-and'th en through auxiliary conhne Lto' the hci'stpush button as hereinhe-" foretr'aced through theylower left'hand pole of the 1 selectorswitch to and through the opera-ting windings ofrelaysyizl and 23 in paralllelg throiigh the normally closed con? tacts-of 'relays si t d;

conta'cts'f'f -oflaccelerating switch 7 to through "the-slack -'ca b1e switches? 28 and 29 to e Inre'spondingrelay21 establishes an fen'ergizing "circuit for reversing switches 5'and '6feirtendihg' from 'line L through the upperpole of switch 36 through one pole of the transfer fswith 71* through the right'hanti pole of relay 21 3 th rough 'anoth er pole 'o'f the transfer' switch 171 to 'andlthrjo'ugh the operating windings of reversing switches 5 and '6' and then through; the lower pole of limitswitch 361toflin'e'IF as already traced; Also, upon closure-of relay'21the sa'rne functions insubstantially the-same manner'as'relay 20lto" establish the afor'edescri bed 'e'nergizing circuits for main switch 2, accelerating switch 15 and the brake switch '18 through t-hmedium' ofthe lower pole of-limitjswitch 36, one of the-poles of transfer switch 71 and auxiliary contacts 7 associated with accelerating switch? and upon closure of reversing switch 5 the contacts 7" are by-passed by auxiliary contacts 5. Also, relay 23 in responding functions in substantially the same manner as relay 22 to shunt the hoist push button, establish an energizing circuit for the slowdown switches 12,13 and 14 and to render the relays associated with the up reversing switches-inoperative; The control mechanism operates'in substantially thesa'me manner as above described to operate the ski hoist in a reverse direction. As the skip hoist moves into its opposite limit limit switches 53. 54, 55 and 36 are operated in the order named to perform substantiallythe same functions as the limit'switches 50, 51, 52 and 37 respectively. 'as'above described.

owever, in this connection should be pole of limit switch 36 resets selector switch 35 through the medium of auxiliary contacts 35. i

The skip hoist can be stopped at any point between limits by opening of the stop push button switch 30 and upon stopping of the skip hoist at any point the selector switch noted that the upper 35 always insures operation of the motor in a direction to raise the loaded bucket upon starting of the motor by'the-hoist pushlbuit- Assuming now that the'skip 'hoist has been stopped in an intermediate posi-? tion while the same was operating in a dilo'werin'g push button 6et-through the ,up' er' left', and contacts o'f selector *"35 through the operating windings of the relays 63 and 66 in parallel,"throughthe normall closed contacts of relays 65a'nd 22,-u1r'o'ugh the lower pole of limit switchj36, through auxiliary contacts 7 associated with seederatin'g switch 7 and the slack cable sjvitches 28" an'd29 to lineL. f Relay 63 in respondingestablishes'an'eiiergizing circuit for. slow'sp eed switchj16 extending from line L through the left hand pole of said relay, through one poleof-the transfer switch 71 ,aiid thence thrduglfthe' operating winding of accelerating switch,'16 to line" L. Upon closure-of accelerating switch-16 the relay 61 is energized-comn'ection thereof in' parallel with'the 'o'p'erat ing winding 'of'fl acceleratingffswitch through the medium ofthe left hand pole of. relay 66. Relay '61 is'eonne'cte'd in shunt, with the relay 21 and performs substantiall the same functions asthe latter. In other words, upon closure of relay '61 the main; switch 2 and reversing switches 5 and 6, accelerating switch15,'brake switch 18are all closed to reverse the direction of the motor for lowering of bucket. Relay 63 in responding maintains itself and relay 66 through the medium of its right hand contacts while the normally closed 'contacts thereof render the timing relay 40 and accelerating switch 7 inoperative to prevent operation of the accelerating switches 7 to 11, inclusive. Also, relay 66 in responding establishes energizing circuits for slow down switches 12, 13 and letthrough the medium of'limit switches 53, 54 and 55, respectively and the auxiliarycontacts associated 'wlth reversing switch 6. Thus it should be noted that during lowering operations of the loaded bucket the series resistance R and shunt resistance R are included in the motor circuit to provide for slow operation of the motor. During lowering of the loaded bucket into its lower limits switches 53, 54 and 55 are opened in the order named to deenergize slow down switches 12, 13 and 14 respectively for inclusion of resistance R,

the loaded of operation forms substantially through movable contacts 73 7 other pole of the and R while upon movement .of the loaded bucket into its lower limits the limit switch 36 is opened to again stop the motor as hereinbefore described. In this connection it should bc noted that the selector switch 35remains in its original position. ,QAssuming now that the skip hoist was operating in adirection corresponding to the reversing. switches 5 and (Sand that the same was stopped at an intermediate point it will be observed that the selector switch 35 is in a position whereby its lower contacts are closed whereby depression of the lowering push button will efiect energization of relays 62, and v( by a circuit extending from line L to the low eifin button as hereinbefore described through the left hand down contact of relay 35 through operating windings ofgrelays 62 and 65 in parallel through the normallyclosedcontacts of relays 23 and 65 through the lower pole;of limit switch 37 through auxiliarjycontacts 7 of accelerating switch 7 and through the slack cable switches 28 and 29 to line L Relay 62 performs substantially the same functions as relay 63 during the hereinbefore described lowering operation of the loaded skip hoist and relay 65 provides for energization of relay by a circuit extending .fromline L through th e left hand pole of relay 62 through one pole of ;the transfer switch 71, throughthe auxiliary contacts of accelerating switch-16 through the left handpole of relay to and through the operating-winding of relay 6O to line L Relay 60 in responding per- I the same function as relay 2Q whereby the motor .is caused to operate in adi rection which is, opposite to that of which it was assumed it was to be last operatmg. a

As before stated the controller includes an emergency control drum which is adapted to act ,through the transfer switch 71 to selectively effect high and low speed operation of the skip hoist in opposite directions. Assuming that the transfer-switch 71 is moved into its upper emergency position the no volt age relay 90 is energized by a circuit extending from line L through one pole of the transfer switch 71 to stationary contact 73 and 72 to stationary contact 72 through another pole of the transfer switch, through the overspeed governor 25, overload devices 26 and 27, an-

transfer switch 71 and thence through the operating winding of the no'voltage relay to line L Upon response of voltage. relay 90 the left hand pole thereof hy-passes contacts 72, 7 2, 73 and 7 3*. Upon movement of the emergency drum 70 towards the left into either its slow or fast speed positions, reversing switches 3 and 4 are energized by a circuit extending from line L through the upper pole of limit switch 37 through a pole of the transfer switch 71 to stationary contact 77 of the master controller and thence through contacts 77", 78*and 78 through another pole of the'transfer switch 71. to and through the operating windings of reversing switches 3 and 4 to line L as hereinbefore traced. Also circuit is established from line L to contact 7 8 as already traced through contacts 7 9 79 to and through the right hand pole of the no voltage relay 90 through one pole of transfer switch 71 and thence to the operating windings of main switch 2 accelerating switch 15 and the brake switch 18. When the master switch is moved towards the right into either its slow or high speed positions the same is adapted to energize the set of reversing switches 5 and 6 by a circuit extending from line L through the upper poleof limit switch 36, throughtrans. fer switch 71 to contact 81 and thence through; contacts 81, 80 and .80, through one pole of transfer switch 71 -to and through the operating windings ofreversing switches 5 and 6 to line L as already-traced; (Also circuit is established from line Lto contact.

81- as already traced through contacts 81."; 79 and 79 toand through the right hand pole of no voltage relay 90, through one pole ofthe ing windings of main'switch 2, accelerating switch 15 and the brake switch 18.

His thus apparent th drum 70 provides for operation in either direction selectively and in this connection'it should be noted that under no.

voltage conditions'no voltage'relay 90 pm" vents re-starting of the motor except upon return of said drum to off position. In other words, the no voltage-relay prevents energize s it h s or: main switch 2,'acceleratmg switch 15 and'the 1 brake switch 18 except upon return of thetion of either set of reversing drum 70 to off position, which serves as hereinbefore describedto establish an energizing circuit for the no voltage relay.

Also when the emergency drum 70 is moved into either of its slow speed positions circuit is established'from line L- through the left hand pole of the no voltage relay 90 to contact 7 2, through contacts 75 or 75 to contact 75 through one pole ofJt-he transfer switch 71 to and through the operating winding of switch 16 to line L tion of the motor and it should be noted that when the drum 70 is moved into either of its fast speed positions such switch is deenergized. The drum 70 is also adapted in both'of its slow and fast speed positions to connect the slow down switches 12, 13 and 14 to line L through the medium of contacts 72, 72*, 74* or 74*, whereby said switches will act in the manner hereinbefore described to effect slow down of the motor during movement of the skip hoist into either of its limits. Upon movement of the drum 70 into either of transfer switch 71 to the operat at the: emerge cy of the motor As before stated re sponse of switch 16 insures slow speed opera 0:: lie

. motor through its fast speed positions the accelerating switches 7 to 11, inclusive, are rendered operative by oy-passing the normally closed contacts of relays 62 and 63 through the medium of contacts 72, 72 76 or 76' and 76.

What I claim as new and desire to secure by Letters Patent is:

1. In combination, two skip buckets, a motor for moving said skip buci-zets oppositely between upper and lower limits, control means for said motor including a selector switch to be set in diti'ercnt positions upon movement of said skip buckets into cor e sponding limits, 2. hoist lowering push button for controlling said the medium of said selector switch and means associated with said forlowering of a loaded bucket.

2. In a skip hoist the combination with two skip buckets, of a motor for operating said bucket-s oppositely between upper and lower limits, starting means for said motor including a selector switch to be set in one position upon movement of one of said skip buckets into agiven limit and in another po sition upon movement of the other of said skip buckets into a corresponding limit, means including a manually operated push button adapted to act through the medium of said selectorswitch to insure operation of the motor in a direction to raise a loaded skip bucket, and a second manually operated switch arranged to act through said selector switch to effect operation of said motor in a direction for lowering of a loaded skip hoist bucket.

The combination with an electric motor. of switches for establishing reverse power connections therefor, and control u'zcans or said reversing switches including a selector switch to be set in difi'erent positions upon operation of said motor in opposite directions through a given range and a single control switch adapted upon successive operations to control said reversing switches through the medium of said selector switch for operation of said motor in opposite directions through said range.

4. The combination with an electric motor, of switches for selectively establishing reverse power connections therefor and control means for said reversing switches including an electroresponsive switch having a plurality of operating windings associated therewith for effecting setting thereof in dili'erent positions upon operation of said motor in opposite directions through a. given range and a manually operated control switch adapted upon successive operations to control said reversing switches through the medium of said selector switch for operation push button and a of said motor in said range.-'

5. The combination with. an electric motor, of switches for selectively establishing re verse power connections therefor and control means for said reversing switchesincluding aselector switch adapted to be set-fin -dif-' ferent positions uoon operation of said" mot r in opposite directions through given range and a plurality" of manually operated switches for controlling said reversing switches through the medium of said selector switch, one of said manually operated being adapted upon successive operations to effect operation of said motor in opposite directions through said range, another being adapted to stop said motor at intermediate points in said range and another being adapted upon stopping of said motor at any intermediate point to restart the same in an opposite direction.

6. The combination with an electric motor, of switches for selectively establishing re verse power connections therefor, a manually operated control switch, means for selectively controlling said reversing switches upon successive operations of said control switch to effect operation of said motor in opposite directions through a given range and push button controlled means associated withsaid 'form'er means for stopping said motor at intermediate points in said range and for restarting the same in an opposite direction.

7. The combination with an electric motor, of electroresponsive switches for selectively establishing reverse power connections therefor, a manually operated control switch, means for selectively controlling said reversing switches upon successive operations of said control switch to effect operation of said motor in opposite directions between given limits at a givenspeed and means for stopping said motor at points between said limits and for restarting the same in an opposite direction at a reduced speed.

8. In combination, a skip bucket, an operating motor therefor. means including a single push button adapted upon successive operations to control said motor for operation of said bucket in opposite directions at a given speed between the loading and dumping positions thereof, and means associated with said former means including a push button for controlling said motor to effect lowering of said bucket from any intermediate point at a reduced speed whenv the same is loaded.

9. In combination, a skip bucket, an operating motor therefor, means including a single push button adapted upon successive operations to control said motor for operation of said bucket in opposite directions at a given speed between the loading and dumping positions thereof and means associated opposite directions through with said former means including a plurality of push buttons, one for controlling said motor to stop said bucket at any intermediate point and the other for controlling said motor to effect lowering of said bucket from any intermediate point at a reduced speed when the same is loaded.

In witness whereof, I have hereunto subscribed my name.

PAISLEY B. HARl/VOOD. 

